The present invention relates to a synchronous induction motor provided with a permanent magnet having a two-pole structure inserted into a rotor yoke portion.
Conventionally, for example, in a refrigerator (an electric refrigerator), an air conditioner (an air conditioning device) and the like, an enclosed type electric compressor constituting a refrigerating cycle of a cooling apparatus thereof is mounted. Furthermore, as an electrically driven element for driving the compressor, there has been employed an induction motor or a DC brushless motor driven by a single phase or three phase commercial power source.
However, in the case of taking an efficiency together with an energy regulation in recent days or the like into consideration, an operation efficiency of the motor used in the enclosed type electric compressor constituting the refrigerant cycle of the refrigerator, the air conditioner or the like does not always have high efficiency. On the contrary, it is said that it is effective to use the DC brushless motor in view of the high efficiency, however, the DC brushless motor requires a drive circuit, so that there is a problem of generating an increase of cost. Accordingly, it is desired to develop a motor which can be operated from a start by a commercial power source and has a high efficiency.
The present invention is made so as to solve the problems of the prior art mentioned above, and an object of the present invention is to provide a synchronous induction motor realizing a great reluctance torque by concentrating a magnetomotive force generated by a rotor provided with a permanent magnet having a two-pole structure, and having a high efficiency.
That is, in accordance with the present invention, there is provided a synchronous induction motor comprises a stator provided with a stator winding, a rotor rotating within the stator, a cage-type secondary electric conductor provided in a peripheral portion of a rotor yoke portion constituting the rotor and a permanent magnet inserted into the rotor yoke portion and having a two-pole structure,
wherein the magnetomotive force generated by one pole of the rotor is set to a value equal to or less than 10% of a peak value in a predetermined range near an electrical angle 0 degrees or 180 degrees.
Further, in accordance with the present invention, there is provided a synchronous induction motor as described above, wherein the range equal to or less than 10% is set to electrical angles 0-10 degrees and 170-180 degrees.
Further, in accordance with the present invention, there is provided a synchronous induction motor as described in each of the inventions mentioned above, wherein the magnetomotive forces generated by the rotor in a range of the electrical angle other than the range equal to or less than 10% are distributed in a sine wave shape.
Further, in accordance with the present invention, there is provided a synchronous induction motor as described in each of the inventions mentioned above, wherein the magnetomotive forces generated by the rotor in a range of the electrical angle than the range equal to or less than 10% are distributed in a step-like chevron shape having two or more steps.
Further, in accordance with the present invention, there is provided a synchronous induction motor as described in each of the inventions mentioned above, wherein the synchronous induction motor is mounted on a compressor.
Further, in accordance with the present invention, there is provided a synchronous induction motor as described above, wherein the compressor is used in an air conditioning device or an electric refrigerator.
In accordance with the present invention, because in the synchronous induction motor having a stator provided with a stator winding, a rotor rotating within the stator, a cage-type secondary electric conductor provided in a peripheral portion of a rotor yoke portion constituting the rotor and a permanent magnet inserted into the rotor yoke portion and having a two-pole structure, the magnetomotive force generated by one pole of the rotor is set to a value equal to or less than 10% of a peak value in a predetermined range near an electrical angle of 0 degrees or 180 degrees, it is possible to concentrate the magnetomotive force generated by the rotor to a range between 10 degrees and 170 degrees which corresponds to a range other than the electrical angles 0-10 degrees and 170-180 degrees by setting the range equal to or less than 10% the electrical angles 0-10 degrees and 170-180 degrees. Accordingly, because it is possible to secure a great reluctance torque, it is possible to achieve a high efficiency and a high torque of the synchronous induction motor.
Further, in accordance with the present invention, because the magnetomotive forces generated by the rotor in a range of the electrical angle other than the range equal to or less than 10% are distributed in a sine wave shape, it is possible to smoothly rotate the rotor. Accordingly, it is possible to make good use of a reluctance torque.
Further, in accordance with the present invention, since the magnetomotive forces generated by the rotor in a range of the electrical angle other than the range equal to or less than 10% are distributed in a step-like chevron shape having two or more steps, it is possible to make the magnetomotive force generated by the rotor having the permanent magnet having the two-pole structure inserted into the rotor yoke portion similar to a sine wave. Accordingly, it is possible to achieve a high efficiency and a high torque without largely deteriorating an effect of the magnetomotive force generated by the rotor.
In particular, if the generated magnetomotive force is, for example, formed in the shape distributed in a step-like chevron shape having two or more steps, it is possible to further improve an effectiveness of a high efficiency and a high torque.
Further, in accordance with the present invention, because the synchronous induction motor mentioned above is mounted on the compressor, it is possible to realize a low energy structure, for example, by using the compressor in the air conditioning device or the electric refrigerator. Accordingly, it is possible to develop a commercial product, for example, corresponding to a recent energy regulation or the like.